| 摘要 |
PROBLEM TO BE SOLVED: To exactly detect a level of base noise superimposed on an output of an in-cylinder pressure sensor.SOLUTION: An ECU 50 calculates an absolute pressure correction value dp of in-cylinder pressure on the basis of the in-cylinder pressure, an in-cylinder capacity and a ratio of specific heat which are obtained from two crane angles during a compression stroke of the same cycle. Then, the ECU calculates a standard difference &sgr;of the absolute pressure correction value dp on the basis of the absolute pressure correction values dp at a plurality of the crank angles, and when the standard difference &sgr;exceeds a prescribed upper-limit determination value &sgr;0, determines that a level of base noise is abnormal. By this arrangement, it can exactly be determined whether the level of the base noise is abnormal on the basis of only an output of an in-cylinder pressure sensor 44, and abnormal conditions of the output of the sensor can easily be detected without using an output of the other sensor supplementally. |
